The use of sheet piles for building retaining walls is well known. The sheet piles used in such walls have sheet pile interlocks along their longitudinal edges, which can be interlocked so as to maintain the longitudinal edges of adjacent sheet piles interconnected with each other. Current sheet pile interlocks of the double-hook interlock type (type 1 according to EN10248 norm), as e.g. LARSSEN type sheet pile interlocks, are hook shaped elements with an internal interlock chamber. A sheet pile wall is formed by driving a first sheet pile into the ground, introducing the bottom end of the trailing sheet pile interlock of a second sheet pile with the top end of the leading sheet pile interlock of the first sheet pile, driving the second sheet pile into the ground, and then repeating the process to insert third, fourth etc sheet piles into the wall.
It is often necessary to secure two interconnected sheet pile interlocks against longitudinal shifting relative to one another. This can be achieved by bonding the interlocked sheet pile interlocks with a fixing agent, like e.g. an adhesive or cement.
U.S. Pat. No. 4,981,540 discloses a method for securing sheet pile interlocks, wherein the interlock chamber of the leading sheet pile interlock is filled with an adhesive, and a caliber piece is applied to the interlock to protect the adhesive and keep soil out of the interlock chamber. Once the sheet pile is driven in, the caliber piece is extracted and a next sheet pile can be driven in. The trailing sheet pile interlock of the next sheet pile is forced into the adhesive filling the interlock chamber in the leading sheet pile interlock of the sheet pile in place in the ground. A major drawback of this method is that the adhesive in the interlock chamber will make the withdrawal of the caliber piece more difficult. Furthermore, an adhesive with a long curing time must be used, as the adhesive must not be allowed to set until the next sheet pile is driven into the ground. According to another method described in U.S. Pat. No. 4,981,540, a caliber piece, having a pipe with nozzles mounted on it, is introduced into the leading sheet pile interlock before the sheet pile is driven in. Once the ramming operation is finished, the caliber piece is withdrawn while an adhesive is simultaneously injected through the pipe nozzles into the interlock chamber. A major drawback of this second method is that a very fluid adhesive must be used, because it has to be injected through a long pipe into the interlock chamber. It is however impossible to warrant a homogeneous distribution of such a fluid adhesive in a vertical interlock chamber, which is subjected to impacts and vibrations during the ramming process of the next sheet pile. In order ensure good bond conditions, it is with both methods important to keep ground material off the contact surfaces of the interlocking sheet pile interlocks. However, when the caliber piece is withdrawn, ground material inevitably mixes with the uncured adhesive, thereby impairing the bond conditions. A further drawback of the above methods is that the interlock head of the trailing sheet pile interlock engaging the interlock chamber of the leading sheet pile interlock progressively acts upon the adhesive in the interlock chamber as a kind of percussive expulsion piston pushing most of the adhesive out of the interlock chamber. In other words, most of the adhesive injected into the interlock chamber is lost in the surrounding ground.
For the sake of completeness it will be mentioned that following prior art documents disclose methods for providing a seal between two interlocked sheet pile locks:
DE 2722978 teaches more particularly to inject a sealing mass in the interlock chamber of a sheet pile and to form by means of a stripping device a shaped seal that is firmly bonded to an internal surface of the interlock chamber. Once the sealing mass has hardened to form an elastic seal in the interlock chamber, the sheet pile is driven into the ground, wherein an interlocking head of a sheet pile previously driven into the ground engages the interlock chamber having the seal therein.
EP 0628662 teaches more particularly to inject a sealing mass in a special sealing chamber defined between two sheet pile interlocks.
BE 1006600 teaches more particularly to fill a sealing mass in an interlock chamber of a sheet pile, wherein a specially shaped mandrel is used to distribute and shape the sealing mass on the internal surfaces of the interlock chambers. Thereafter, the first sheet pile is interlocked with a second sheet pile, and both sheet piles are then jointly driven into the ground.
GB 2322658 teaches more particularly to fill the interlock chamber of a sheet pile, which is already driven into the ground, with a hardening sealant. It suggests using an injection conduit, which is retractably inserted in the interlock chamber and driven into the ground at the same time as the sheet pile. Once this sheet pile is in position, the sealant is pumped through the injection conduit into the interlock chamber, while the injection conduit is simultaneously drawn upwards out of the interlock chamber. Once the injection conduit has been entirely removed from the interlock chamber, a second sheet pile can be driven into the ground in an interlocking relationship with the first sheet pile.
JP 01-207520 teaches to fill the interlock chambers of a first sheet pile and of a second sheet pile with a foaming resin prior to driving them into the ground. Once the foaming resin is hardened in the interlock chambers, the sheet piles can be driven in sequence into the ground, wherein the hardened foaming resin should prevent the infiltration of sediment into a joint section, facilitate the driving and prevent the deformation and damage of the sheet piles.